1. Field of the Invention
This invention relates to a tuck-in apparatus for a weaving loom.
2. Description of the Related Art
One known type of a pneumatic tuck-in apparatus as disclosed in published Japanese Examined Utility Model Application No. 6-16952 includes a body disposed outside a warp yarn end, tuck-in nozzles disposed in the body, the nozzles having two axes extending in an intersecting relationship to one another, in which air blowing from one of the nozzles folds back a proximal end of a weft yarn end, while air blowing from the other nozzle drives a distal end of the weft yarn end toward a cloth fell, both of the nozzles continue to blow air until weft insertion or beating is completed.
Although one of the tuck-in nozzles need not continue to blow air until the end of the weft insertion after the weft yarn end is folded back, it must continue to blow air because these two nozzles are communicated to a single air passage in the body. As a result, a large quantity of air is consumed in total. Similarly, the other nozzle must uselessly continue to blow air. In order to reduce a period of time for a blast of air, the nozzles may be caused to stop blowing air after the weft yarn end is folded back, but may be allowed to resume blowing air immediately before the closing of a warp shed in order to force the weft yarn end toward the cloth fell. However, one of these two nozzles that simultaneously blow air is again unnecessary, and a large quantity of air is consumed after all.
A needle type tuck-in apparatus is designed to insert and swing a needle into the warp shed through between warp yarns so as to extend outside the warp arrays in order to grip the weft yarn end by means of a distal end of the needle, and thereafter to release the weft yarn end and then swing the needle so as to pull the needle out of the warp shed, thereby folding back the weft yarn end toward the cloth fell. This system slackens the weft yarn end without any constraint imposed by the needle, and consequently often produces a loosened tuck-in selvage. A countermeasure for avoiding such a shortcoming is that timing in which the needle is pulled from the warp shed is delayed until immediately before the closing of the warp shed in order to allow the warp yarns to retain the weft yarn end at the same time when the weft yarn end is released.
While the above countermeasure provides a successfully fastened tuck-in selvage, increased contact between the needle and the warp yarns damages the warp yarns, resulting in woven fabric defects such as a needle trace.
An object of the present invention as defined in claim 1 is to provide a tuck-in apparatus developed in view of the above and designed to provide a successfully fastened tuck-in selvage without unnecessary air blowing, with a consequential reduction in manufacturing cost.
Another object of the present invention as defined in claim 2 is to provide a tuck-in apparatus designed to form a woven fabric having a successfully fastened tuck-in selvage without needle traces.
A further object of the present invention as defined in claim 3 is to provide a tuck-in apparatus adapted for different weaving conditions such as kinds of weft yarns.
An aspect of the present invention as defined in claim 1 provides a tuck-in apparatus including a tuck-in nozzle for injecting air into a warp shed from the outside of warp arrays in order to fold back a weft yarn end toward a cloth fell, characterized by: a selvage-fastening nozzle disposed adjacent to the cloth fell outside the warp arrays for causing the weft yarn end folded back by the tuck-in nozzle to extend along the cloth fell, wherein air injection from the tuck-in nozzle and that from the selvage-fastening nozzle are separately controllable, and wherein air injection start timing of the selvage-fastening nozzle is later than that of the tuck-in nozzle, but is set to be put before the warp shed is closed.
The phrase xe2x80x9ca selvage-fastening nozzle disposed adjacent to the cloth fell outside the warp arrays for causing the weft yarn end folded back by the tuck-in nozzle to extend along the cloth fellxe2x80x9d means that a woven fabric edge of the cloth fell lies within a range of air injection from the selvage-fastening nozzle. As a specific example, a nozzle holder including a weft yarn end-introducing slit is provided with the tuck-in nozzle and the selvage-fastening nozzle. More specifically, a selvage-fastening holder has an injection orifice positioned adjacent to the cloth fell and opened through a side surface of the nozzle holder toward the warp arrays. The woven fabric edge of the cloth fell lies within a range of air injection.
The phrase xe2x80x9cair injection start timing of the selvage-fastening nozzle is later than that of the tuck-in nozzlexe2x80x9d means that the air injection start timing of the selvage-fastening nozzle is earlier than, simultaneous with, and later than air injection end timing of the tuck-in nozzle. When the former is earlier than the latter, then air injection timing of the selvage-fastening nozzle overlaps with that of the tuck-in nozzle. When the former is simultaneous with and later than the latter, then there is no overlap between the air injection timing of the selvage-fastening nozzle and that of the tuck-in nozzle. The absence of such an overlap means that the air injection timing of the selvage-fastening nozzle is delayed with reference to that of the tuck-in nozzle, but continues at least until the warp shed is closed. The phrase xe2x80x9cbut continues at least until the warp shed is closedxe2x80x9d means that air injection is allowed to stop before the warp shed is closed, and is also allowed to resume after the warp shed is closed. Since air blowing after the closing of the warp shed exercises no influences on how a tuck-in selvage is fastened, it is ideally desirable in view of cost that the air injection timing ends just with or immediately before the closing of the warp shed. However, since a tuck-in operation is effected instantly, it is difficult to match the end of the tuck-in operation exactly with the closing of the warp shed.
While one aspect of the invention as defined in claim 1 is directed to the pneumatic tuck-in apparatus, another aspect of the invention as defined in claim 2 provides a tuck-in apparatus having a needle swung and thereby inserted into a warp shed through between warp yarns so as to extend outside warp arrays in order to grip a weft yarn end, the needle being thereafter swung to be pulled out of the warp shed, thereby releasing and then folding back the weft yarn end toward the cloth fell, characterized by: a selvage-fastening nozzle disposed adjacent to the cloth fell outside the warp arrays for causing the weft yarn end folded back by the needle to extend along the cloth fell, wherein air injection timing of the selvage-fastening nozzle may continue between the moment the need releases the weft yarn end and at least the moment the warp shed is closed.
The selvage-fastening nozzle may be immovable in the direction of the warp, or alternatively may be provided so as to be movable in the direction of the warp, as defined in claim 3.
The phrase xe2x80x9cthe selvage-fastening nozzle may be provided so as to be movablexe2x80x9d means that the single selvage-fastening nozzle may be movably provided, or alternatively the selvage-fastening nozzle integrally combined with the tuck-in nozzle may be movably disposed. As defined in claim 3, for different weaving conditions such as a kind of the weft, a weft density, and a woven fabric structure, the selvage-fastening nozzle can be moved near the cloth fell, even when the cloth fell moves toward the warp.